1. Technical Field
The present invention relates to wrenches.
2. Description of Related Art
Wrench is the most widely used hand tool to lock and unload. It can be divided into ratchet wrench, socket wrench and so many types.
A wrench requires different strength when the locking device is locked on a different machine, especially a precise machine. However, the general wrench can't measure the torsion when using. It is easy to affect the safety of the machine.